Traditionally, images projected by projectors are often twisted or rotated because the platforms for arranging the projectors are uneven. Therefore, to prevent the twist or rotation of images, projectors often have adjustable support leg.
FIG. 5 shows a traditional screw-typed support leg for use with projectors. The support leg 508 includes a support portion 510 and a screw portion 504. A contact between the support portion 502 and a platform 502 generates a friction force. When adjusting the support leg 508, users have to exert a larger force to overcome the friction force to rotate the screw portion 504. In addition, when raising up or dropping down the projectors with a long interval, users have to rotate the screw portion 504 for many circles.
FIG. 6 shows another adjustable support leg, which is disclosed in Japanese Patent Publication No. 11-271879. This support leg includes a bar 610, a rack 612, and springs 614a and 614b. The bar 610 is movably disposed on a housing 602. The bar 610 includes an extension portion 610a for controlling the bar 610 and a latch 610b for engaging with the rack 612. The spring 614a connects the housing 602 with the bar 610 and forces the latch 610b to engage with the rack 612. When adjusting the support leg, users may push the extension portion 610a to move the latch 610b and release the rack 612.